Microsoft today released the RTM (release to manufacturing) of Windows Phone 7 marking a milestone in Windows Phone development. Windows Phones are said to be hitting the market this holiday season. No word yet which models are included in the first wave. Here is the info from Microsoft's Windows Phone blog:

Today is the day that the Windows Phone team has been driving towards, and we?re very excited to say that we?ve reached the biggest milestone for our internal team ? the release to manufacturing (RTM) of Windows Phone 7! While the final integration of Windows Phone 7 with our partners? hardware, software, and networks is underway, the work of our internal engineering team is largely complete.

Windows Phone 7 is the most thoroughly tested mobile platform Microsoft has ever released. We had nearly ten thousand devices running automated tests daily, over a half million hours of active self-hosting use, over three and a half million hours of stress test passes, and eight and a half million hours of fully automated test passes. We?ve had thousands of independent software vendors and early adopters testing our software and giving us great feedback. We are ready.